Alessio Attardo: Aberrant synaptic dynamics precede disorganization of activity patterns in the hippocampus upon repeated stress exposure
| When |
May 24, 2022
from 05:15 PM to 06:00 PM |
|---|---|
| Where | Hybrid Format in the Lecture Hall, Bernstein Center. Zoom ID and password will be sent with e-mail invitation. You can also contact Fiona Siegfried for Meeting ID and password. |
| Contact Name | Fiona Siegfried |
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Hybrid Format!
Abstract
Stress exposure affects the structure and function of hippocampal CA1 leading to disruption of episodic memory. Drawing a connection between changes in structural connectivity and activity patterns upon repeated stress has been a major issue to this point. Even in rodents, the vast majority of previous experimental work focused either on structure or on function, resulting in separate streams of findings using different stress paradigms and models. To solve this issue, we took an integrative approach and combined wide field head-mounted miniaturized microscopes, longitudinal deep-brain two-photon optical imaging and a behavioral task to study the relationship between deficiencies of structural activity and connectivity in hippocampal CA1 pyramidal neurons and the ability to learn in mice undergoing repeated stress.
We found that repeated stress exposure led to immediate and sustained increase in neuronal activity and to a delayed disorganization of the temporal structure of this activity and loss of spatial coding content of dorsal hippocampal CA1 pyramidal neurons. In addition, thanks to the longitudinal nature of our in vivo two-photon imaging, we could track - for the first time - structural excitatory connectivity of dorsal hippocampal CA1 pyramidal neurons over one week of repeated stress. This enabled us to detect a significant decrease in excitatory connectivity occurring in two separate steps: an immediate but transient decrease in spinogenesis followed by a delayed increase in spine loss. Interestingly, spine loss in CA1 pyramidal neurons only became apparent after several days of hyperactivity, and disorganization of the temporal structure of activity and loss of spatial coding content was evident only after significant spine loss. Thus, suggesting that the effects of stress exposure on hippocampal temporal and spatial coding are mediated by loss of synaptic connectivity.
